The Topaz Solar Farm under construction in California Valley in the southeastern corner of San Luis Obispo County is now producing 300 megawatts of power.

With that accomplishment, the plant became, albeit fleetingly, the largest utility-scale photovoltaic plant in the world, said Dawn Legg, spokeswoman for First Solar, the energy company building the facility.

When complete a year from now, the plant will produce 550 megawatts of power, enough electricity to power 160,000 homes.

Another First Solar plant under construction in Riverside County, called Desert Sunlight, will also produce 550 megawatts. That plant is also expected to achieve 300 megawatts within a month or so, matching the Topaz plant’s production, Legg said.

The milestone is notable because the plant is now supplying a significant amount of energy to the state’s electrical grid, Legg said. Construction on the sprawling plant began in 2011.

“We’ve been talking about this for a long time, and we are now getting there,” she said.